The Symptoms
When Jennifer Schwartzott was 12 years old, she began to feel totally drained of energy. She was an active girl and swam competitively, but she knew something was wrong.

I couldnt make it a short distance in the pool, she remembers.

Her family doctor tested her for mononucleosis, a common virus in adolescents whose hallmark symptoms are fatigue and swollen glands, but the labs came back negative. The doctor tested her again. Still negative. It wasnt mono.

Without a diagnosis, Schwartzott stopped swimming, but her exercise intolerance persisted. In high school, when she was instructed to run a mile for a P.E. class, she ended up in the emergency room with shortness of breath.

Once more, doctors came up frustratingly short.

Despite her lack of both answers and energy, she wasnt about to slow down. She jumped into her life as eagerly as shed once jumped into the pool. When she got to college at 17, she took on a full class load, extracurricular activities, and work.

That was when the stress dangerously took its toll. Several times, she experienced stroke-like episodes. She didnt have blood clots in her brain, but it was malfunctioning in a way that produced similar symptoms. Her entire left side drooped. Both her eyes were squeezed shut, and she had to hold them open with her fingers. But the cause remained a mystery.

Now 44, Schwartzott realizes that back in those days, nobody was diagnosing her rare condition. Most doctors had never heard of it. Eventually she would be one of the first people in the Buffalo area who was diagnosed.

One doctor told my parents I was doing it for attention, she says.

Others suggested she had Bells Palsy, multiple sclerosis, or lupus. But those possibilities quickly were ruled out. One thing was clear: Schwartzott needed to ease up. She went down to a part-time class load, stopped working, and went on disability. The more she slowed down, the more she improved.

Fast-forward four years to the birth of her daughter, who was nearly 10 pounds. Her body couldnt handle the trauma of childbirth, and afterward, she became pretty much a vegetable. She had trouble breathing and moving after the birth, and her eyelids drooped. This last symptom proved to be the key to unlocking the mystery.

If I did not have droopy eyelids, she says, I would never have been diagnosed back then.

The Diagnosis
Specialists were called in to her hospital room to figure out what was wrong. One of the doctors, an out-of-town physician who happened to be visiting Buffalo for a medical conference, asked if her eyelids were always like that. She said yes.

What he said next would shed light on her whole life:
It might be mitochondrial disease.

Mitochondria are specialized compartments found in every cell except for red blood cells. They are the bodys powerhouse  they convert food and oxygen into energy. But for people with mitochondrial disease, there are defects in this crucial part of the cell caused by maternally inherited genetic mutations.

About 1 in 5,000 to 10,000 people are symptomatic from the disease, though as many as 1 in 200 people carry mitochondrial mutations. Not all people who carry mutations show symptoms, says Dr. Michio Hirano, a professor of neurology at Columbia University Medical Center.

There are hundreds of copies of mitochondrial DNA in each cell, explains Dr. Hirano, who has been treating Schwartzott for the past 20 years. If you have a low level of mutations, like 10 to 20 percent, you wont have symptoms. Its only when your mutation exceed 70 percent that you will show symptoms.

The disease mainly affects children, but adult onset also occurs. Theres a wide spectrum of symptoms and severity. Some kids born with the disease are so ill they pass away devastatingly young, while some affected adults can live relatively normal lives. Other adults may not know they have it until they suddenly fall ill. The most common symptoms are exercise intolerance, muscle and nerve pain, and severe fatigue. The more extreme symptoms that can lead to death are diabetes, heart and lung problems, and seizures.

For Schwartzott, a muscle biopsy in the hospital confirmed her diagnosis.

But the relief of knowing the truth was soon accompanied by a deeper distress: There was  and still is  no cure.

The Aftermath
After her diagnosis, Schwartzott continued to have stroke-like episodes, causing major memory loss and loss of function on her left side. Managing mitochondrial disease is about treating individual symptoms until someday, hopefully, researchers find a cure. Shes now lived with it for more than 20 years.

Every day varies, she says. On a good day, she can get up in the morning and work part-time as an auto-racing official, a beloved job she has held for 26 years. Shes been a pit marshal at all the big race tracks such as Daytona and Watkins Glen, and has worked with Nascar, Indycar, IMSA, and SCCA.

But on bad days, her energy is so depleted, she cant get out of bed. She also suffers from muscle and nerve pain, as well as joint pain from psoriatic arthritis. (Its very common for patients with mitochondrial disease to develop autoimmune diseases like arthritis.)

She has no peripheral vision in either eye and her eyeballs are paralyzed, so she cant move them back and forth. You just learn to turn your head more, she says.

But one surgery on her right-eye muscles has helped, and another surgery to implant a special intraocular lens improved her vision tremendously. Eventually, she plans to have a surgery to lift her droopy lids so they will be more functional.

Ive had some disastrous blind dates, she says with a good-natured laugh. Its very hard to date with mitochondrial disease. Some guys are afraid they might catch it. However, she adds, her symptoms have progressed more slowly than some other patients.

Part of the reason for that may be the experimental drug she is currently taking, called EPI743. She is one of three patients of Dr. Hirano in a clinical trial at Columbia University, though the drug is being tested at medical centers around the world.

For the past several years, she has injected a liquid syringe of the compound into her mouth three times a day. Dr. Hirano says that it seems to function as an antioxidant, reducing toxic damage caused to cells by the defective mitochondria.

Its helped with my eye functioning, Schwarzott notes. My lids arent as hard to control, and the headaches around my eyes are pretty much gone. I believe its also helped with my cognitive ability and memory.

Still, she cant remember what its like to be healthy: She can no longer climb stairs, run, ski, or bike. But at heart, shes just as adventurous as shes always been.

Im very big on finding quality of life, she says firmly. Im not the kind of person whos going to sit at home and do nothing and wait to die.

Besides traveling and working, she volunteers for a patient advocacy group called The United Mitochondrial Disease Foundation, which has raised more than $10 million since 1996 to put toward medical research for treatments and diagnostic tools.

The good news for new patients, she says, is that diagnosis is much easier than it used to be two decades ago. Diagnostic criteria has been developed, so doctors are more educated and know what to look for.

But until that elusive cure is found, she returns time and again to emphasizing the importance of quality of life. The night we spoke, shed gone out with friends despite feeling ill because seeing them mattered too much to skip.

I often pay for the fun I have, but it was worth it, she said, speaking from her bed with her eyes closed. Even if youre diagnosed with something like this, you can still find things you enjoy that make life worth living.

Kira Peikoff is the author of No Time to Die, a thriller about a girl who mysteriously stops aging. It is available now for pre-order, and will be published on Sept. 2, 2014. Follow Kira on Facebook or Twitter.

If youve endured a medical mystery and want to share your story, email Kira at cosmomysterydiagnosis@gmail.com.